1. Field of the Invention
The invention relates to a method for finishing a building board, in particular of a wood material, plastic or a mixture of wood material and plastic with a top side and an underside and opposite side edges, and a building board.
2. Discussion of Background Information
Building boards, e.g., flooring panels or wall and ceiling panels, are provided with a wood, stone or fantasy pattern with a superimposed, three-dimensional surface. The wood material boards have connecting mechanisms (e.g., tongue and groove) and are usually equipped with locking mechanisms for locking adjacent boards in the horizontal and vertical direction. A realistic optical and tactile impression of the imitated material is produced through the superimposition of a pattern and three-dimensional surface.
In particular, flooring panels are coated at least on the top side and have a pattern and a structure adapted to the pattern. A structure of this type is called a pattern-synchronous structure. The pattern is present either as a paper layer laminated to the support board or as a paint coat printed directly onto the support board. Moreover, the pattern is coated in an abrasion-resistant manner. To this end, either abrasion-resistant paper layers, so-called overlays, or varnish coats which are abrasion-resistant after curing are used.
MDF, HDF, chipboard or OSB boards as well as plastic boards are used as support boards. The pattern-synchronous structure is present as a three-dimensional surface structure and is embossed into the board surface by a correspondingly three-dimensionally structured pressing plate. The constituents of the coating that can be activated thermally and under pressure melt and flow and fill up the three-dimensional structural embossing and cure. The structure has a height of up to 500 μm, preferably 100 to 200 μm. The number and the depth of the structures are limited, on the one hand, by the available amount of constituents that can be activated and, on the other hand, by the press force.
In the production of building boards of this type, the patterning always takes place first followed by the application of the pattern-synchronous structure.
U.S. Pat. No. 6,401,415 B1 describes a laminate that is provided on the surface with impregnated cellulose sheets in which a structure is embossed in a mechanical press. The finished pressed boards have an optical and tactile texture that corresponds to the pattern of the surface.
U.S. Pat. No. 6,688,061 B2 describes a laminate material that contains cellulose sheets that have been impregnated with a polymer resin and mechanically pressed and cut. The laminate material has a surface with an external area, an edge contour and an internal area, whereby the external area is sunk so that the edge contour lies below the internal area. A structure is mechanically made in the surface of the edge contour that differs from the optical impression of the surface and imitates a different product.
U.S. Pat. No. 6,638,387 B2 describes a method for embossing a structure into building products. In U.S. Pat. No. 6,638,387 B2, a precured decorative paper with a decorative motif is placed on a board. Reference points are formed on the board before the placement of the decorative paper. The decorative paper is impregnated with melamine resin and the board is then transported into a press that has a three-dimensionally structured press plate. The building board is aligned via the reference points such that the three-dimensional structure of the press plate and the decorative motif coincide so that the pattern and the structure of the press plate correspond to one another. The resin-impregnated paper is cured in the press to embody the laminate material and to produce a product that has a surface texture that exhibits an embossing that corresponds to the respective decorative motif.
However, such techniques have a disadvantage in the use of paper sheets bearing patterns. By way of example, considerable effort in terms of adjustment is necessary in order to compensate for the undefined paper growth through the printing and pressing in order to allow the pattern lines and structure and relief of the embossing to run synchronously with one another. It is a particular disadvantage that the relief and structure are embossed on top in the coating, whereby the optical and tactile impression of a natural product cannot be evoked or can be evoked only very inadequately.